The mowing or grinding devices comprise a rotatable shaft which carries tools which operate in the manner of flails during the rotation of the shaft. The rotatable shaft is provided with flanges which are positioned perpendicularly with respect to its axis, carry axial supports, which are arranged parallel to the axis of the rotatable shaft, and support the tools. The tools can be directly mounted on the axial supports. In this case, the tools are each provided with a mounting aperture through which one of the axial supports passes. The tools can also be mounted on the axial supports by means of shackles. In this case, each shackle comprises, on the one hand, mounting apertures through which an axial support passes which is carried by flanges which are connected to the rotatable shaft and, on the other hand, an axial support passes through a mounting aperture of the tool. Said assemblies are realized in such a manner that the tools and the shackles can turn freely with respect to the axial supports.
Thus, on the one hand, when the rotatable shaft is rotated, the tool is capable of being arranged in an operating position in which it extends radially with respect to the rotatable shaft under the effect of the centrifugal force. On the other hand, the tools can be retracted by the rotation of the shackle and/or the rotation of the tool so as to move away from their operating position when they come into contact with obstacles that they cannot cut or grind. Such a mowing or grinding device is described notably in French patent FR 2 944 182.
Furthermore, in the aforesaid document, the axial supports and the mounting apertures have forms which fit into one another when the tool is in its operating position so as to favor keeping the tool in the operating position. Said document discloses a large variety of forms of axial supports which are capable of telescoping into a complementary portion of the mounting aperture, for example triangular or octagonal overall. Such axial supports and mounting apertures allow optimum positioning of the tool in its operating position to be ensured compared to assemblies in which the axial supports have a circular section and the mounting apertures are oblong. Said assembly therefore allows the tools to return more quickly to their operating position whilst limiting the vibrations of the tools around their operating position.
It has nevertheless been noted that such axial supports and mounting apertures have been subject to wear and to rapid matting which impairs the service life of the mowing or grinding device which has been realized in this manner.